A study is proprosed of the function and regulation of neutral secretory proteases in keratinocyte-mediated interstitial collagen and basement-membrane degradation. (1) The ability of live keratinocytes to degrade interstitial type I and III collagen fibrils in culture will be measured and the specific and coordinate role of the component proteases of the collagenolytic complex: a 65K collagenase, a 110K gelatinase, two (70K and 48K) plasminogen activators and exogenous plasminogen will be analyzed by immune-inhibition. A search will be made for additional components of the collagenolytic complex such as specific activators of procollagenase and plasminogen proactivators and the regulatory role of plasma and endogenous secretory protease inhibitors, including epidermal inhibitors of the fibrinolytic and collagenolytic systems, will be analyzed. (2) The ability of keratinoyctes to degrade intact basement membranes will be investigated. The component proteases of the type IV collagen, laminin, fibronectin and heparan sulfate proteoglycan degrading systems will be identified and the specific function of the type IV-collagen-degrading protease system will be analyzed by specific immune inhibition. (3) The expression of proteolytic competence as a function of basal cell activation will be investigated. (a) The inverse relationship between secretion of specific proteases and terminal differentiation induced by anchorage deprivation in vitro will be established and the distribution and position of secretor cells in surface-attached primary explants and in clonal colonies will be correlated with that of differentiation markers. (b) The synthesis of proteases by activated basal cells induced by excision wounding in vivo will be studied by immunofluorescence and correlated with migration, confluence and stratification during the healing process. (c) The effect on interstitial collagen and basement membrane degradation of agents which modulate expression of activated and differentiated cellular states such as retinoids, glucocorticoids, inflammatory agents and cyclic nucleotides will be analyzed.